Polyarteritis Nodosa - PAN

Polyarteritis nodosa (PAN) is a necrotizing vasculitis resulting in aneurysmal formation and organ infarction. It is categorized as a medium-vessel vasculitis (Chapel Hill, 2012).


Indications for Testing

Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)

Laboratory Testing

  • Nonspecific testing – helpful in excluding other diagnoses or identifying organ dysfunction
    • CBC – rule out infection
    • Urinalysis (UA) – hematuria, proteinuria, red blood cell casts
    • C-reactive protein (CRP) – frequently elevated
  • Testing to consider to rule out other diagnoses


  • Small- and medium-size artery necrotizing vasculitis with absence of glomerulonephritis
  • Arterioles, capillaries, and/or venules – most affected
  • Immunofluorescence fails to demonstrate complement or immunoglobulin in vessel walls

Imaging Studies

Angiography – microaneurysms and stenoses of medium vessels.

Differential Diagnosis



  • Incidence –16-25/million for systemic vasculitis as a group (includes eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis, polyarteritis nodosa, and granulomatosis with polyangiitis)
  • Age – peak onset in 50s
  • Sex – M:F, equal

Risk Factors

Chronic hepatitis B

Clinical Presentation

  • Constitutional – fever, malaise, weight loss, arthralgias
  • Cardiovascular – acute coronary syndrome
  • Dermatological – vascular purpura, livedo reticularis, lower extremity ulcers, subcutaneous ulcers
  • Gastrointestinal – nonspecific abdominal pain, gastrointestinal bleeding, bowel perforation
  • Neurological – mononeuropathy multiplex
  • Renal – renovascular hypertension, vascular nephropathy



  • Age – peak is 9-11 years
  • Sex – M<F, slight

Clinical Presentation

  • Tends to be a more limited disorder than in adults
  • Constitutional – fever, malaise, weight loss
  • Musculoskeletal – arthritis/arthralgia, myositis, myalgia
  • Renal – vascular hypertension, hematuria, proteinuria
  • Neurological – peripheral neuropathy
  • Gastrointestinal – nonspecific abdominal pain
  • Dermatological – livedo reticularis, skin nodules, skin infections

Indications for Testing

Unexplained systemic illness with multiple system involvement (renal, neurologic, dermatologic)

Laboratory Testing

  • Nonspecific testing
    • CBC – anemia, leukocytosis, thrombocytoses
    • C-reactive protein (CRP) – usually elevated
    • Urinalysis (UA) – proteinuria, hematuria, red cell casts
    • Electrolytes – increases in blood urea nitrogen (BUN)/creatinine not uncommon
  • Antineutrophil cystoplastic antibodies (ANCA) – rarely positive

Differential Diagnosis

ARUP Laboratory Tests

Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)

Preferred first-line reflex panel for the evaluation of ANCA-associated vasculitis

Components: ANCA, IgG; MPO, IgG; PR3, IgG

Can be ordered as part of the acute hepatitis panel which includes hepatitis A virus (HAV) IgM, hepatitis B virus (HBV) core antibody IgM, HBV surface antigen (HBsAg), and hepatitis C virus (HCV) antibody; refer to acute hepatitis panel with reflex to HBsAg confirmation

Reflex pattern: if results for HBsAg screen are repeatedly reactive with an index value between 1.00 and 50.00, then HBsAg confirmation will be added

Aid in initial diagnosis of connective tissue disease

Positive nuclear patterns reported include homogeneous, speckled, centromere, nucleolar, or nuclear dots; positive cytoplasmic patterns reported include reticular/AMA, discrete/GW body-like, polar/golgi-like, rods and rings, or cytoplasmic speckled patterns

Results are not disease specific

Lower sensitivity than ANA IFA for systemic autoimmune rheumatic diseases

Reflex pattern: if ANA are detected by ELISA, then ANA, HEp-2, IgG by IFA will be added

Detect glomerular basement membrane (GBM) antibodies in suspected or established anti-GBM disease

May be useful for monitoring treatment response

Positive result should be confirmed by renal biopsy

Panel includes GBM antibody, IgG by multiplex bead assay and IFA

Related Tests

Detect acute or chronic hepatitis B virus (HBV) infection

Medical Experts



Patricia R. Slev, PhD, D(ABCC)
Professor of Pathology (Clinical), University of Utah
Section Chief, Immunology; Medical Director, Immunology Core Laboratory, ARUP Laboratories